Delft University of Technology
Faculty Mechanical, Maritime and Materials Engineering Transport Technology
B.A. Liebrand Verificatie van de theorie van verticale schroeftransporteurs (2 dln.). Masters thesis, Report 96.3.TT.4698, Transport Engineering and Logistics.
The vertical screwconveyer is a machine that is used to transport bulk cargo along a certain height. This is done by means of a rotating screw which is driven by an electromotor. The screw turns in a pipe which is fed with bulk cargo by a hole at the lower end of the pipe. This can be done for example by means of a bunker. The screw transports the bulk cargo along the pipe and throws it out through a hole at the upper end of the pipe. By varying the input parameters, like the rotation frequency and the mass input, the output magnitudes, like the mass flow and the efficiency, can be changed.
The company 'Van Beek screwconveyer systems' develops and fabricates screwconveyers. This is done by means of a computer-program, which displays values for the output magnitudes as a function of the input parameters. The Technical University of Delft has also developed some computer-programs which are based on the theory of vertical screwconveyers.
The values for the output magnitudes of these computer-programs are however hardly confirmed by practical experiments. It's not clear what the efficiency is of the screwconveyers made by Van Beek, or what the influence is of the different parameters on the process. It's therefore necessary to verify the output magnitudes of these computer-programs by means of experiments. To do this a test unit has been developed and fabricated, with which the different output magnitudes can be examined.
The starting-point of this test unit is a screwconveyer which is in main lines equal to a conveyer with a bunker built by Van Beek as a standard. The conveyer has been changed to obtain the necessary test results.
The results that are found with the test unit are used to verify the computer programs. The main conclusions based on the results of the test unit are: The values that are calculated by the computer-program of Van Beek for the rotation frequency and the power supply that have to be provided are too low. The company is aware of the fact that the power supply that has to be provided is too low: from the motor-catalogue a motor is chosen which can provide a bigger power supply than the value that is created by the computer-program. Increasing the rotation frequency could improve the efficiency.
The values that are generated by the computer-programs of the Technical University of Delft are similar to the values that are obtained with the test unit, but are highly sensitive to the coefficient of friction between the screw and the bulk cargo. Also must be observed, that the values which are generated by the computer-programs are only verified for one type of screwconveyer.
Reports on Transport Engineering and Logistics (in Dutch)
